Polarized ringing device for use in telephone systems



1957 H. v. ALEXANDERSSON ETAL 2,782,4w

POLARIZED RINGING DEVICE FOR USE IN TELEPHONE SYSTEMS 3 Sheets-Sheet 1 Filed Jan. 15, 1954 HHHH U IHHHM H H irrok/viy Feb 1957 H. v. ALEXANDERSSON ET AL 2,782,410

POLARIZED RINGING DEVICE FOR USE IN TELEPHONE SYSTEMS s Sheets-Sheet 2 Filed Jan. 15, 1954 I N VEN T0 as HHR/un Macs/7m? fizimA/amssam H546: fave/w .Z/NMr/v 5/1 3r ML 9770 RM! r 1957 H. v. ALEXANDERSSON ETAL 2,732,410

POLARIZED RINGING DEVICE FOR USE IN TELEPHONE SYSTEMS Filed Jan. 15, 1954 s Shets-Sheet 5 MAZQ Haw.

United States Patent POLARIZED RINGING DEVICE FOR USE IN TELEPHONE SYSTEMS Harald Valdemar Alexandersson, Lidingo, and Helge Edvard Lindstriim, Stuvsta, Sweden, assignors to Telefonaktiebolaget L M Ericsson, Stockhohn, Sweden, a corporation of Sweden Application January 15, 1954, Serial No. 464,314

Claims priority, application Sweden January 30, 1953 Claims. (Cl. 349-697) This invention refers to improvements in polarized A. C. ringers to effect a preferably adjustable damping of the sound output of the ringer. The invention has especially for an object to satisfy the want to make the subscriber himself able to regulate the damping of the ringer in a simple manner within rather wide limits.

The invention will be more closely described with reference to the annexed drawing, which shows an embodiment in connection with a telephone instrument.

Fig. l is a plan View of the device, Figs. 2 and 3 a plan view of a detail with the parts in different positions. Fig. 4 is a side view with one gong broken away and Fig. 5 shows the device from in front.

in the drawings 1 indicates the electromagnet of the ringer, whose armature 2, mounted approximately in the middle and carrying the clapper 3, can oscillate between the pole shoes 4, 5 and 4a, 5a. 6 indicates the gongs of the ringer and 27 the bottom plate of the apparatus. Fixed to the armature 2 is a leaf spring 7, which with its free end, provided with a depression 8, rests against a pin 9 projecting from the bottom plate 27, said pin being provided with a sleeve of nylon. The arm 7 may be pressed against the pin 9 by means of one end 12 of a coil spring 13 (Figs. 4, 5), the other end of which is fixed, whereby the pressure is transmitted by means of a stud 11 of nylon. The coil spring 13 is mounted on a holder 14 (Figs. 4, 5) passing through the bottom plate 27 and provided with a flange 15 resting against the inside of the plate. The holder 14 is provided with an axial boring, which is threaded and in which a screw 16 is threaded, said screw being provided with a head 19. On the upper end of said screw there is threaded a nut 18. A washer 17 is positioned between the holder and the nut. The holder 14 may be turned from the under-side of the bottom plate by turning the screw head 19. The lower end 22 of the coil spring 13 is held between two flaps 23 projecting from the flange 15 (Fig. 5), for which reason the tension of the coil spring, when 11 rests against '7, may be varied, when the holder 14 is turned. A stop 24 on the flange 15 cooperates with a pin 25 (Fig. 1) fixed to the bottom plate and limits the turning of the holder 14. In the position of the parts shown in Fig. 1 the stud 11 rests against the arm 7 with maximum pressure and the turning of the holder in a clockwise direction is blocked by the pin 25. When the holder is turned counterclockwise the tension of the coil spring is reduced and the pressure, with which the stud 11 presses the leaf spring 7 against the pin 9, is reduced.

If the armature 2, from its middle position shown in Fig. 1, is attracted by one of the pole shoes 4, 5 a certain movement energy is supplied to the armature, which energy during the movement of the armature to one of its end positions is partly absorbed in the form of friction when the arm 7 moves between the pin 9 and the stud 11. The clapper 3 will accordingly strike the gong with less strength than if there had been no friction 2,782,410 Patented Feb. 19, 1&5?

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between the arm 7 and the pin 9. The harder the arm 7 is pressed against the pin 9, the greater portion of the movement energy of the armature will be absorbed in the form of friction and the less becomes the sound output emitted by the ringer. The sound output may obviously be varied within wide limits by turning the screw head 19.

T he above mentioned depression 8 on the leaf spring 7 is intended to centre the spring '7 in such a position, that the armature 2 in rest position is located half-way between the pole shoes 4, 5 (the position shown in Pig. 1). If such a centering does not exist the armature 2, when the ringer is not energized, will take a position close to one of the pole shoes 4, 5 and, if the ringer is heavily damped (great pressure between the leaf spring 7 and the pin 9) there will arise starting difliculties for the armature. Because the armature, thanks to the centering device, is held in middle position, said starting difiiculties are eliminated. For a definite degree of damping there is needed less magnetomotive force from one of the pole shoes to bring the armature from the middle position to the mentioned pole shoe than for bringing the armature from the opposite pole shoe to the mentioned pole shoe. The device can of course function even if the arm "7 has no depression but, as mentioned, when strongly damped, the start of the armature is aggravated.

Fig. 2 shows the position when the holder 14 has been turned not quite a revolution counterclockwise from the position shown in Fig. 1, whereby the stop 24 is again blocked by the pin 25. In this position the stud 11 does not press the arm 7 against the pin 9 and the friction between the arm 7 and the pin 9 is inconsiderable. The depression 3 on the arm 7 moves, during the oscillations of the armature, apart from the degree of damping, between an upper limit and a lower one, the lower limit being shown in Fig. 2 and the upper limit in Fig. 3.

The previously mentioned washer 17, which takes part in the movement of the screw 16, is in a place at the periphery provided with a flap 26, which is bent downwards (see particularly Fig. 4). When the screw 16 is turned counterclockwise it will, in a fixed position, strike against the spring end 12 and carry it with itself, when the turning is continued, in a counterclockwise direction. in Pig. 2 there is shown a position, in which the flap 26 has caused the spring end 12 to move some degrees in a counterclockwise direction, so that the stud 11 does not rest against the arm 7. The screw 16 with the washer 17 is in this position blocked against further turning in a counterclockwise direction, because the stop 24 has struck the pin 25. When the stud 11 takes this position the arm 7, when suitably adjusted, is able to move between the arm 7 and the stud 11 without any friction or with a friction that is dependent on the tension with which the arm (the leaf spring) 7 rests against the pin 9. It is now possiblein the position according to Fig. 2to prestress the coil spring 13 so that the spring end 12 with a suitable pressure rests against the flap 26 and consequently (in Fig. 2) endeavours to move clockwise. if, outgoing from this position, in which the damping is supposed to be zero, the screw 16 with the stop 26 is turned clockwise, the spring end 12 will at first follow the movement of the flap 26 until it strikes the arm 7. If the screw 16 is turned still further, the disengagement of the coil spring against the stop 26 will cease and the spring end 12 with the stud 11 will press against the arm 7 with the previously adjusted prestress. Thus is achieved-practically already at the contact between 11 and 7-that a certain pressure, which is adjustable in advance, is obtained between 11 and 7 and that the continued turning of the screw 16 (not quite a revolution until the stop 24 strikes the pin 25 on the other side) may be wholly utilized to increase the damping. The device may be used even if the washer 17 is not provided with said flap 26, but has the same diameter round about, but in this case the pressure between the stud 11 and the arm '7, after they have come in contact with each other, will be and (by experience on a certain embodiment) the screw 16 had to be turned /2 revolution before the ear caught any damping of the sound output. A turning of only half a revolution is in this case left to regulate the damping. The device for prestressing the coil spring will thus give a greater regulating range. The pin 9 and the stud 11 have been indicated as coated with nylon, which has proved to be especially suitable in this case. Of course, any other material giving a suitable friction may be used.

We claim:

1. An A. C. operated polarized ringing device including a bell striker for use in telephone systems, said device comprising solenoid means including a vibratory armature means for actuating the striker, and means for partially damping the vibratory energy of the armature means generated by energizing the solenoid means, said damping means including fixed abutment means and a member extending from said armature means and slidably engaging said abutment means, the pressure of the engagement between the member and the abutment means controlling the damping of the vibratory energy ofthe armature means.

2. An A. C. operated polarized ringing device including a bell striker for use in telephone systems, said device comprising solenoid means including a vibratory armature means for actuating the striker, and means for partially damping the vibratory energy of the armature means generated by energizing the solenoid means, said damping means including fixed abutment means and a member extending from said armature means and slidably engaging said abutment means and yielda-ble means biasing said member and said fixed abutment means toward each other, the pressure of the engagement between the member and the abutment means controlling the damping of the vibratory energy of the armature means.

3. A ringing device according to claim 2, wherein said yieldable means comprise a spring engageable at one end with said abutment means, and means for varying the loading of said spring.

4. A ringing device according to claim 2, wherein said armature means comprise a magnitizable member and a springy arm extending from said member for vibration in unison therewith, and wherein said abutment means comprise a pin stationarily mounted perpendicular to said arm, and wherein sm'd yieldable means comprise 'a coil spring, one end of said spring being held and the other coacting with said arm for biasing the latter against said pin.

5. A ringing device according to claim 4, wherein said pin is cylindrical and said arm is formed with an indentation fitting said cylindrical pin, said arm, upon vibration of the armature means, performing longitudinal reciprocatory movements transversly to the axis of the pin causing said indentation to slide into and out of engagement with the pin thereby varying the pressure between the pin and the arm for correspondingly damping the energy of the move ments of the armature means.

6. A ringing device according to claim 5 and further comprising a casing for said solenoid means and said damping means, and a holder mounted in a wall of said casing and supporting said spring, said holder detaining the respective end of the spring and including adjustable means for varying the tension of the spring to control the bias exerted by the other spring end upon said arm, said adjustable means being accessible and operable from the outside of said casing.

7. A ringing device according to claim 6, wherein said coil spring is loaded so as to bias the end thereof coacting with the arm to move toward the arm, and wherein said holder supports an abutment member movable into a position abutting against said spring end coacting with the arm.

8. A ringing device according to claim 7, wherein said solenoid means include a core structure forming pole faces facing each other in spaced relationship, said armature means being disposed between said pole faces and wherein said indentation in the arm is disposed to engage the pin when the armature means are in the position midway between said pole faces.

9. A ringing device according to claim 2, wherein said armature means comprise a magnetizable member and an elongated member extending from the magnetiza'ble member and coacting with said abutment means, and wherein the part of said elongated member coacting with the abutment means and the respective part of the yieldable means are sheathed with nylon.

10. A ringing device according'to claim 2, wherein said yieldable means comprise a spring engageable on one end with said abutment means, and means for varying the loading of said spring, said spring being pro-loaded.

References Cited in the file of this patent UNITED STATES PATENTS 1,182,726 Wetmore May 9, I916 2,324,696 Hannaford July 20, 1943 2,547,537 Power Apr. 3, 1951 2,643,634 Hoyka June 30, 1953 

